High temperature copolyester monofilaments are known in the art. Examples of such copolyester monofilaments are disclosed in PCT International Patent Application No. WO 90/12918. These monofilaments differ from conventional high molecular weight polyester monofilaments in that they exhibit substantially different physical properties. For example, a high temperature copolyester monofilament extruded from a copolyester resin and produced by Shakespeare Monofilament of Columbia, S.C., has a melt point of 285.degree. C. as compared to a conventional high molecular weight polyester monofilament, produced by the same company, which has a melt point of 260.degree. C. The high temperature copolyester monofilament is advantageous in its use in that it exhibits improved resistance to hydrolytic degradation which makes this monofilament more suitable for use in dryer fabrics.
However, an undesirable property associated with the standard high temperature copolyester monofilament is that it exhibits a substantially lower knot tenacity as compared to the conventional high molecular weight polyester monofilament. As noted at page 6 of the bulletin "High Temperature Monofilaments Comparison" furnished by Shakespeare Monofilament of Columbia, S.C., WP-550, a conventional high molecular weight polyester monofilament produced from a 0.95 I.V. polyethylene terephthalate (PET) resin, exhibits an average knot tenacity of 3.5 grams per denier (gpd) as compared to HPP-50, a standard high temperature copolyester monofilament, which exhibits an average knot tenacity of only 1.8 gpd.
Thus, a need exists for a high temperature copolyester monofilament having improved knot strength and enhanced knot tenacity.